Hawking radiation doesn't "Escape" a black hole. In empty space, there is a constant seething foam of particle-antiparticle pairs that get created all the time.
My understanding is that those particles in "empty" space are virtual particles, but the intense gravitational field at an event horizon coerces them into becoming real particles. The ones that escape were a product of the black hole's gravity energy, hence they have taken some of its energy away with them. This could even cause a black hole to shrink over time, apparently. Its been a while since I read any of this stuff tho.